High costs of extracting greenhouse gases from thin air could tumble with new technologies that can help to combat climate change, scientists said on Thursday.

Carbon Engineering, a Canadian-based clean energy company, outlined the design of a large industrial plant that it said could capture carbon dioxide from the atmosphere at a cost of between $94 and $232 a tonne.

That is well below past estimates of about $600 a tonne by the American Physical Society, said David Keith, a Harvard University physics professor and the founder of Carbon Engineering who led the research.

An artist’s impression of Carbon Engineering’s large industrial plant that it said could capture carbon dioxide from the atmosphere at a cost of between $94 and $232 a tonne.

‘I hope to show that this as a viable energy industrial technology, not something that is a magic bullet … but something that is completely doable,’ he told Reuters of the peer-reviewed study published in the journal Joule.

Carbon Engineering, which has about 40 employees and produces about a tonne of carbon dioxide a day from an experimental plant.

The firm is owned by several private investors, including Bill Gates.

The technology makes synthetic fuels using only air, water and renewable power.

Keith said an industrial-scale plant could make fuel at a dollar a litre.

That would be competitive in California, where low carbon fuel standards to cut pollution from cars and trucks mean high prices.